gdb/corelow.c

   1 /* Core dump and executable file functions below target vector, for GDB.
   2
   3    Copyright 1986, 1987, 1989, 1991, 1992, 1993, 1994, 1995, 1996,
   4    1997, 1998, 1999, 2000, 2001, 2003, 2004 Free Software Foundation,
   5    Inc.
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 2 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 59 Temple Place - Suite 330,
  22    Boston, MA 02111-1307, USA.  */
  23
  24 #include "defs.h"
  25 #include "arch-utils.h"
  26 #include "gdb_string.h"
  27 #include <errno.h>
  28 #include <signal.h>
  29 #include <fcntl.h>
  30 #ifdef HAVE_SYS_FILE_H
  31 #include <sys/file.h>           /* needed for F_OK and friends */
  32 #endif
  33 #include "frame.h"              /* required by inferior.h */
  34 #include "inferior.h"
  35 #include "symtab.h"
  36 #include "command.h"
  37 #include "bfd.h"
  38 #include "target.h"
  39 #include "gdbcore.h"
  40 #include "gdbthread.h"
  41 #include "regcache.h"
  42 #include "regset.h"
  43 #include "symfile.h"
  44 #include "exec.h"
  45 #include "readline/readline.h"
  46
  47 #include "gdb_assert.h"
  48
  49 #ifndef O_BINARY
  50 #define O_BINARY 0
  51 #endif
  52
  53 /* List of all available core_fns.  On gdb startup, each core file register
  54    reader calls add_core_fns() to register information on each core format it
  55    is prepared to read. */
  56
  57 static struct core_fns *core_file_fns = NULL;
  58
  59 /* The core_fns for a core file handler that is prepared to read the core
  60    file currently open on core_bfd. */
  61
  62 static struct core_fns *core_vec = NULL;
  63
  64 /* FIXME: kettenis/20031023: Eventually this variable should
  65    disappear.  */
  66
  67 struct gdbarch *core_gdbarch = NULL;
  68
  69 static void core_files_info (struct target_ops *);
  70
  71 #ifdef SOLIB_ADD
  72 static int solib_add_stub (void *);
  73 #endif
  74
  75 static struct core_fns *sniff_core_bfd (bfd *);
  76
  77 static int gdb_check_format (bfd *);
  78
  79 static void core_open (char *, int);
  80
  81 static void core_detach (char *, int);
  82
  83 static void core_close (int);
  84
  85 static void core_close_cleanup (void *ignore);
  86
  87 static void get_core_registers (int);
  88
  89 static void add_to_thread_list (bfd *, asection *, void *);
  90
  91 static int ignore (CORE_ADDR, char *);
  92
  93 static int core_file_thread_alive (ptid_t tid);
  94
  95 static void init_core_ops (void);
  96
  97 void _initialize_corelow (void);
  98
  99 struct target_ops core_ops;
 100
 101 /* Link a new core_fns into the global core_file_fns list.  Called on gdb
 102    startup by the _initialize routine in each core file register reader, to
 103    register information about each format the the reader is prepared to
 104    handle. */
 105
 106 void
 107 add_core_fns (struct core_fns *cf)
 108 {
 109   cf->next = core_file_fns;
 110   core_file_fns = cf;
 111 }
 112
 113 /* The default function that core file handlers can use to examine a
 114    core file BFD and decide whether or not to accept the job of
 115    reading the core file. */
 116
 117 int
 118 default_core_sniffer (struct core_fns *our_fns, bfd *abfd)
 119 {
 120   int result;
 121
 122   result = (bfd_get_flavour (abfd) == our_fns -> core_flavour);
 123   return (result);
 124 }
 125
 126 /* Walk through the list of core functions to find a set that can
 127    handle the core file open on ABFD.  Default to the first one in the
 128    list if nothing matches.  Returns pointer to set that is
 129    selected. */
 130
 131 static struct core_fns *
 132 sniff_core_bfd (bfd *abfd)
 133 {
 134   struct core_fns *cf;
 135   struct core_fns *yummy = NULL;
 136   int matches = 0;;
 137
 138   /* Don't sniff if we have support for register sets in CORE_GDBARCH.  */
 139   if (core_gdbarch && gdbarch_regset_from_core_section_p (core_gdbarch))
 140     return NULL;
 141
 142   for (cf = core_file_fns; cf != NULL; cf = cf->next)
 143     {
 144       if (cf->core_sniffer (cf, abfd))
 145         {
 146           yummy = cf;
 147           matches++;
 148         }
 149     }
 150   if (matches > 1)
 151     {
 152       warning ("\"%s\": ambiguous core format, %d handlers match",
 153                bfd_get_filename (abfd), matches);
 154     }
 155   else if (matches == 0)
 156     {
 157       warning ("\"%s\": no core file handler recognizes format, using default",
 158                bfd_get_filename (abfd));
 159     }
 160   if (yummy == NULL)
 161     {
 162       yummy = core_file_fns;
 163     }
 164   return (yummy);
 165 }
 166
 167 /* The default is to reject every core file format we see.  Either
 168    BFD has to recognize it, or we have to provide a function in the
 169    core file handler that recognizes it. */
 170
 171 int
 172 default_check_format (bfd *abfd)
 173 {
 174   return (0);
 175 }
 176
 177 /* Attempt to recognize core file formats that BFD rejects. */
 178
 179 static int
 180 gdb_check_format (bfd *abfd)
 181 {
 182   struct core_fns *cf;
 183
 184   for (cf = core_file_fns; cf != NULL; cf = cf->next)
 185     {
 186       if (cf->check_format (abfd))
 187         {
 188           return (1);
 189         }
 190     }
 191   return (0);
 192 }
 193
 194 /* Discard all vestiges of any previous core file and mark data and stack
 195    spaces as empty.  */
 196
 197 static void
 198 core_close (int quitting)
 199 {
 200   char *name;
 201
 202   if (core_bfd)
 203     {
 204       inferior_ptid = null_ptid;        /* Avoid confusion from thread stuff */
 205
 206       /* Clear out solib state while the bfd is still open. See
 207          comments in clear_solib in solib.c. */
 208 #ifdef CLEAR_SOLIB
 209       CLEAR_SOLIB ();
 210 #endif
 211
 212       name = bfd_get_filename (core_bfd);
 213       if (!bfd_close (core_bfd))
 214         warning ("cannot close \"%s\": %s",
 215                  name, bfd_errmsg (bfd_get_error ()));
 216       xfree (name);
 217       core_bfd = NULL;
 218       if (core_ops.to_sections)
 219         {
 220           xfree (core_ops.to_sections);
 221           core_ops.to_sections = NULL;
 222           core_ops.to_sections_end = NULL;
 223         }
 224     }
 225   core_vec = NULL;
 226   core_gdbarch = NULL;
 227 }
 228
 229 static void
 230 core_close_cleanup (void *ignore)
 231 {
 232   core_close (0/*ignored*/);
 233 }
 234
 235 #ifdef SOLIB_ADD
 236 /* Stub function for catch_errors around shared library hacking.  FROM_TTYP
 237    is really an int * which points to from_tty.  */
 238
 239 static int
 240 solib_add_stub (void *from_ttyp)
 241 {
 242   SOLIB_ADD (NULL, *(int *) from_ttyp, &current_target, auto_solib_add);
 243   re_enable_breakpoints_in_shlibs ();
 244   return 0;
 245 }
 246 #endif /* SOLIB_ADD */
 247
 248 /* Look for sections whose names start with `.reg/' so that we can extract the
 249    list of threads in a core file.  */
 250
 251 static void
 252 add_to_thread_list (bfd *abfd, asection *asect, void *reg_sect_arg)
 253 {
 254   int thread_id;
 255   asection *reg_sect = (asection *) reg_sect_arg;
 256
 257   if (strncmp (bfd_section_name (abfd, asect), ".reg/", 5) != 0)
 258     return;
 259
 260   thread_id = atoi (bfd_section_name (abfd, asect) + 5);
 261
 262   add_thread (pid_to_ptid (thread_id));
 263
 264 /* Warning, Will Robinson, looking at BFD private data! */
 265
 266   if (reg_sect != NULL
 267       && asect->filepos == reg_sect->filepos)   /* Did we find .reg? */
 268     inferior_ptid = pid_to_ptid (thread_id);    /* Yes, make it current */
 269 }
 270
 271 /* This routine opens and sets up the core file bfd.  */
 272
 273 static void
 274 core_open (char *filename, int from_tty)
 275 {
 276   const char *p;
 277   int siggy;
 278   struct cleanup *old_chain;
 279   char *temp;
 280   bfd *temp_bfd;
 281   int ontop;
 282   int scratch_chan;
 283
 284   target_preopen (from_tty);
 285   if (!filename)
 286     {
 287       error (core_bfd ?
 288              "No core file specified.  (Use `detach' to stop debugging a core file.)"
 289              : "No core file specified.");
 290     }
 291
 292   filename = tilde_expand (filename);
 293   if (filename[0] != '/')
 294     {
 295       temp = concat (current_directory, "/", filename, NULL);
 296       xfree (filename);
 297       filename = temp;
 298     }
 299
 300   old_chain = make_cleanup (xfree, filename);
 301
 302   scratch_chan = open (filename, O_BINARY | ( write_files ? O_RDWR : O_RDONLY ), 0);
 303   if (scratch_chan < 0)
 304     perror_with_name (filename);
 305
 306   temp_bfd = bfd_fdopenr (filename, gnutarget, scratch_chan);
 307   if (temp_bfd == NULL)
 308     perror_with_name (filename);
 309
 310   if (!bfd_check_format (temp_bfd, bfd_core) &&
 311       !gdb_check_format (temp_bfd))
 312     {
 313       /* Do it after the err msg */
 314       /* FIXME: should be checking for errors from bfd_close (for one thing,
 315          on error it does not free all the storage associated with the
 316          bfd).  */
 317       make_cleanup_bfd_close (temp_bfd);
 318       error ("\"%s\" is not a core dump: %s",
 319              filename, bfd_errmsg (bfd_get_error ()));
 320     }
 321
 322   /* Looks semi-reasonable.  Toss the old core file and work on the new.  */
 323
 324   discard_cleanups (old_chain); /* Don't free filename any more */
 325   unpush_target (&core_ops);
 326   core_bfd = temp_bfd;
 327   old_chain = make_cleanup (core_close_cleanup, 0 /*ignore*/);
 328
 329   /* FIXME: kettenis/20031023: This is very dangerous.  The
 330      CORE_GDBARCH that results from this call may very well be
 331      different from CURRENT_GDBARCH.  However, its methods may only
 332      work if it is selected as the current architecture, because they
 333      rely on swapped data (see gdbarch.c).  We should get rid of that
 334      swapped data.  */
 335   core_gdbarch = gdbarch_from_bfd (core_bfd);
 336
 337   /* Find a suitable core file handler to munch on core_bfd */
 338   core_vec = sniff_core_bfd (core_bfd);
 339
 340   validate_files ();
 341
 342   /* Find the data section */
 343   if (build_section_table (core_bfd, &core_ops.to_sections,
 344                            &core_ops.to_sections_end))
 345     error ("\"%s\": Can't find sections: %s",
 346            bfd_get_filename (core_bfd), bfd_errmsg (bfd_get_error ()));
 347
 348   /* If we have no exec file, try to set the architecture from the
 349      core file.  We don't do this unconditionally since an exec file
 350      typically contains more information that helps us determine the
 351      architecture than a core file.  */
 352   if (!exec_bfd)
 353     set_gdbarch_from_file (core_bfd);
 354
 355   ontop = !push_target (&core_ops);
 356   discard_cleanups (old_chain);
 357
 358   p = bfd_core_file_failing_command (core_bfd);
 359   if (p)
 360     printf_filtered ("Core was generated by `%s'.\n", p);
 361
 362   siggy = bfd_core_file_failing_signal (core_bfd);
 363   if (siggy > 0)
 364     /* NOTE: target_signal_from_host() converts a target signal value
 365        into gdb's internal signal value.  Unfortunately gdb's internal
 366        value is called ``target_signal'' and this function got the
 367        name ..._from_host(). */
 368     printf_filtered ("Program terminated with signal %d, %s.\n", siggy,
 369                      target_signal_to_string (target_signal_from_host (siggy)));
 370
 371   /* Build up thread list from BFD sections. */
 372
 373   init_thread_list ();
 374   bfd_map_over_sections (core_bfd, add_to_thread_list,
 375                          bfd_get_section_by_name (core_bfd, ".reg"));
 376
 377   if (ontop)
 378     {
 379       /* Fetch all registers from core file.  */
 380       target_fetch_registers (-1);
 381
 382       /* Add symbols and section mappings for any shared libraries.  */
 383 #ifdef SOLIB_ADD
 384       catch_errors (solib_add_stub, &from_tty, (char *) 0,
 385                     RETURN_MASK_ALL);
 386 #endif
 387
 388       /* Now, set up the frame cache, and print the top of stack.  */
 389       flush_cached_frames ();
 390       select_frame (get_current_frame ());
 391       print_stack_frame (deprecated_selected_frame,
 392                          frame_relative_level (deprecated_selected_frame), 1);
 393     }
 394   else
 395     {
 396       warning (
 397                 "you won't be able to access this core file until you terminate\n\
 398 your %s; do ``info files''", target_longname);
 399     }
 400 }
 401
 402 static void
 403 core_detach (char *args, int from_tty)
 404 {
 405   if (args)
 406     error ("Too many arguments");
 407   unpush_target (&core_ops);
 408   reinit_frame_cache ();
 409   if (from_tty)
 410     printf_filtered ("No core file now.\n");
 411 }
 412
 413
 414 /* Try to retrieve registers from a section in core_bfd, and supply
 415    them to core_vec->core_read_registers, as the register set numbered
 416    WHICH.
 417
 418    If inferior_ptid is zero, do the single-threaded thing: look for a
 419    section named NAME.  If inferior_ptid is non-zero, do the
 420    multi-threaded thing: look for a section named "NAME/PID", where
 421    PID is the shortest ASCII decimal representation of inferior_ptid.
 422
 423    HUMAN_NAME is a human-readable name for the kind of registers the
 424    NAME section contains, for use in error messages.
 425
 426    If REQUIRED is non-zero, print an error if the core file doesn't
 427    have a section by the appropriate name.  Otherwise, just do nothing.  */
 428
 429 static void
 430 get_core_register_section (char *name,
 431                            int which,
 432                            char *human_name,
 433                            int required)
 434 {
 435   char section_name[100];
 436   struct bfd_section *section;
 437   bfd_size_type size;
 438   char *contents;
 439
 440   if (PIDGET (inferior_ptid))
 441     sprintf (section_name, "%s/%d", name, PIDGET (inferior_ptid));
 442   else
 443     strcpy (section_name, name);
 444
 445   section = bfd_get_section_by_name (core_bfd, section_name);
 446   if (! section)
 447     {
 448       if (required)
 449         warning ("Couldn't find %s registers in core file.\n", human_name);
 450       return;
 451     }
 452
 453   size = bfd_section_size (core_bfd, section);
 454   contents = alloca (size);
 455   if (! bfd_get_section_contents (core_bfd, section, contents,
 456                                   (file_ptr) 0, size))
 457     {
 458       warning ("Couldn't read %s registers from `%s' section in core file.\n",
 459                human_name, name);
 460       return;
 461     }
 462
 463   if (core_gdbarch && gdbarch_regset_from_core_section_p (core_gdbarch))
 464     {
 465       const struct regset *regset;
 466
 467       regset = gdbarch_regset_from_core_section (core_gdbarch, name, size);
 468       if (regset == NULL)
 469         {
 470           if (required)
 471             warning ("Couldn't recognize %s registers in core file.\n",
 472                      human_name);
 473           return;
 474         }
 475
 476       regset->supply_regset (regset, current_regcache, -1, contents, size);
 477       return;
 478     }
 479
 480   gdb_assert (core_vec);
 481   core_vec->core_read_registers (contents, size, which,
 482                                  ((CORE_ADDR)
 483                                   bfd_section_vma (core_bfd, section)));
 484 }
 485
 486
 487 /* Get the registers out of a core file.  This is the machine-
 488    independent part.  Fetch_core_registers is the machine-dependent
 489    part, typically implemented in the xm-file for each architecture.  */
 490
 491 /* We just get all the registers, so we don't use regno.  */
 492
 493 static void
 494 get_core_registers (int regno)
 495 {
 496   int status;
 497
 498   if (!(core_gdbarch && gdbarch_regset_from_core_section_p (core_gdbarch))
 499       && (core_vec == NULL || core_vec->core_read_registers == NULL))
 500     {
 501       fprintf_filtered (gdb_stderr,
 502                      "Can't fetch registers from this type of core file\n");
 503       return;
 504     }
 505
 506   get_core_register_section (".reg", 0, "general-purpose", 1);
 507   get_core_register_section (".reg2", 2, "floating-point", 0);
 508   get_core_register_section (".reg-xfp", 3, "extended floating-point", 0);
 509
 510   deprecated_registers_fetched ();
 511 }
 512
 513 static void
 514 core_files_info (struct target_ops *t)
 515 {
 516   print_section_info (t, core_bfd);
 517 }
 518 \f
 519 static LONGEST
 520 core_xfer_partial (struct target_ops *ops, enum target_object object,
 521                    const char *annex, void *readbuf,
 522                    const void *writebuf, ULONGEST offset, LONGEST len)
 523 {
 524   switch (object)
 525     {
 526     case TARGET_OBJECT_MEMORY:
 527       if (readbuf)
 528         return (*ops->to_xfer_memory) (offset, readbuf, len, 0/*write*/,
 529                                        NULL, ops);
 530       if (writebuf)
 531         return (*ops->to_xfer_memory) (offset, readbuf, len, 1/*write*/,
 532                                        NULL, ops);
 533       return -1;
 534
 535     case TARGET_OBJECT_AUXV:
 536       if (readbuf)
 537         {
 538           /* When the aux vector is stored in core file, BFD
 539              represents this with a fake section called ".auxv".  */
 540
 541           struct bfd_section *section;
 542           bfd_size_type size;
 543           char *contents;
 544
 545           section = bfd_get_section_by_name (core_bfd, ".auxv");
 546           if (section == NULL)
 547             return -1;
 548
 549           size = bfd_section_size (core_bfd, section);
 550           if (offset >= size)
 551             return 0;
 552           size -= offset;
 553           if (size > len)
 554             size = len;
 555           if (size > 0 &&
 556               ! bfd_get_section_contents (core_bfd, section, readbuf,
 557                                           (file_ptr) offset, size))
 558             {
 559               warning ("Couldn't read NT_AUXV note in core file.");
 560               return -1;
 561             }
 562
 563           return size;
 564         }
 565       return -1;
 566
 567     default:
 568       if (ops->beneath != NULL)
 569         return ops->beneath->to_xfer_partial (ops->beneath, object, annex,
 570                                               readbuf, writebuf, offset, len);
 571       return -1;
 572     }
 573 }
 574
 575 \f
 576 /* If mourn is being called in all the right places, this could be say
 577    `gdb internal error' (since generic_mourn calls breakpoint_init_inferior).  */
 578
 579 static int
 580 ignore (CORE_ADDR addr, char *contents)
 581 {
 582   return 0;
 583 }
 584
 585
 586 /* Okay, let's be honest: threads gleaned from a core file aren't
 587    exactly lively, are they?  On the other hand, if we don't claim
 588    that each & every one is alive, then we don't get any of them
 589    to appear in an "info thread" command, which is quite a useful
 590    behaviour.
 591  */
 592 static int
 593 core_file_thread_alive (ptid_t tid)
 594 {
 595   return 1;
 596 }
 597
 598 /* Fill in core_ops with its defined operations and properties.  */
 599
 600 static void
 601 init_core_ops (void)
 602 {
 603   core_ops.to_shortname = "core";
 604   core_ops.to_longname = "Local core dump file";
 605   core_ops.to_doc =
 606     "Use a core file as a target.  Specify the filename of the core file.";
 607   core_ops.to_open = core_open;
 608   core_ops.to_close = core_close;
 609   core_ops.to_attach = find_default_attach;
 610   core_ops.to_detach = core_detach;
 611   core_ops.to_fetch_registers = get_core_registers;
 612   core_ops.to_xfer_partial = core_xfer_partial;
 613   core_ops.to_xfer_memory = xfer_memory;
 614   core_ops.to_files_info = core_files_info;
 615   core_ops.to_insert_breakpoint = ignore;
 616   core_ops.to_remove_breakpoint = ignore;
 617   core_ops.to_create_inferior = find_default_create_inferior;
 618   core_ops.to_thread_alive = core_file_thread_alive;
 619   core_ops.to_stratum = core_stratum;
 620   core_ops.to_has_memory = 1;
 621   core_ops.to_has_stack = 1;
 622   core_ops.to_has_registers = 1;
 623   core_ops.to_magic = OPS_MAGIC;
 624 }
 625
 626 /* non-zero if we should not do the add_target call in
 627    _initialize_corelow; not initialized (i.e., bss) so that
 628    the target can initialize it (i.e., data) if appropriate.
 629    This needs to be set at compile time because we don't know
 630    for sure whether the target's initialize routine is called
 631    before us or after us. */
 632 int coreops_suppress_target;
 633
 634 void
 635 _initialize_corelow (void)
 636 {
 637   init_core_ops ();
 638
 639   if (!coreops_suppress_target)
 640     add_target (&core_ops);
 641 }